JP4493598B2 - Adjustable pitch propeller with feathering blade and shock absorber, especially for sailing ships - Google Patents

Abstract

The lifetime of plural shock absorbing resilient inserts of an adjustable pitch propeller with feathering blades may be increased. According to an embodiment, stops are implemented between metal surfaces that may be reached only in the event of shocks of great violence and following a certain elastic deformation of the shock absorbing inserts, which remain partially compressed. At the bottom of each circular cavity housing a respective annular insert of elastomer of the flange of a first cylindrical sleeve directly keyed on the drive shaft of the propeller a hole coaxial and of greater diameter than the diameter of a central hole of the annular insert and of the relative engaging pin is formed. Pins projecting from the face of the terminal flange of a second circular sleeve extend through the coaxially formed holes at the bottom of the respective circular cavities of the flange of the first sleeve.

Description

In sailing ships, the use of feathering blades, that is, propellers with blades that can orient themselves by rotating, has become widespread to reduce drag during sailing when idle.
On the other hand, to maximize overall efficiency when driven by a motor, the propeller adds to the engine characteristics (torque and efficiency characteristics as a function of revolutions per minute), as well as the hull hydrodynamics and even navigation Sometimes it must be in the dominant condition.

An effective solution to these requirements is the so-called variable-pitch propeller, i.e., within a certain limit, the blades of the (screw) propeller are adjusted to the specific characteristics and / or usage conditions. Produced by a propeller that can change its direction.
Among the commercially available propellers, there is a class known as variable pitch propellers with feathering blades, which are used with auxiliary engines, especially in sailing ships.
Typically, these propellers consist of pinion hubs that are fixed or otherwise rotated about the drive shaft, and the pinion hubs engage two or more planetary gears at the base of the prop blade blade handle.

Each blade has its handle rotatably held in a hole in the outer shell, but when the planetary gear moves on the conical pinion hub, there are two limitations facing the center or neutral position of the blade. It can rotate at an angle about the axis of the basic planetary gear, at which the two main surfaces of the blade are substantially parallel to the drive shaft due to the hydraulic forces acting on it. The limiting angle is preset by a suitable stop device that determines the propeller pitch in two directions of rotation.
The outer shell, usually formed by joining parts with tangential screws, houses a plurality of blade pinion hubs and planetary gears rotatably held in respective holes penetrating the wall of the outer shell. Of course, the outer shell is pulled by the blade that is engaged with the pinion hub in a planetary manner around its axis, or the blade is pulled, so that the outer shell can freely move around the axis of the pinion hub within the aforementioned limited angle in the direction of the blade. Can rotate.

The stopping positions of the arcs that are allowed to rotate around the pinion hub axis are preset by the cooperative action of sector teeth or radial teeth that are in contact with each other and one of which is mechanically connected to the pinion hub and the other. The stop position in the mutual rotation direction of the two parts is determined.
Such types of propellers are described in US Pat. No. 4,047,841 and US Pat. No. 4,140,434.
In these known propellers, the pitch can only be changed by disassembling the propeller, and therefore the boat needs to be lifted from the water each time the pitch needs to be changed.
In Italian patent 1,214,251 by the same applicant, a feathering blade propeller is disclosed, the pitch of which can be adjusted without disassembling the propeller.

For this purpose, a sleeve is used which can be engaged at a different angular position with the pinion hub body and which is held engaged by a spring.
Pull the handle of the sleeve through the shaft hole at the head end of the propeller outward against the contraction force applied by the spring to disengage the sleeve from the pinion hub, and then pull it at a different angle on the pinion hub Re-engage in position, thus changing the pitch.
In subsequent Italian patents Nos. 1,235,687 and 1,235,831 by the same applicant, a further improved propeller of this type is disclosed, whereby the outer side against the force exerted by the contraction spring is disclosed. Simply pull a part of the shell and move the above part of the outer shell away from the fixed part of the outer shell a sufficient distance to disengage the mating joint with the teeth between the two parts of the outer shell After angular rotation, it was possible to release and re-engage the movable part with the fixed part of the outer shell at the desired changed angular position to adjust the pitch.

A further advantage of the propellers disclosed in the latter two patents mentioned above is the improved mounting method of the blade made rotatable by the restraining and supporting shell and the elasticity between the abutment surfaces of the end stop. By introducing a cushioning material having, it was brought about by reducing the impact when starting to rotate the propeller in one or the other direction.
All these propellers with adjustable internal movement mechanism for torque transmission from the drive shaft to the pinion hub and eventually to the outer blade assembly of the propeller will rotate especially when docked or other causes Since the direction is reversed infinitely (forward thrust / backward thrust), the audible shock noise during repeated operations is prevented or reduced, and at the same time, the metal stop surface of the cooperating part of the propeller's internal torque transmission mechanism In order to reduce wear and deformation of the blade, it is very important to mitigate the impact caused by the impact of the face of the end stop that determines the degree of freedom of rotation of the planetary blades.

Even if the blade hits a suspended object while the motor is running, even the accidental impact will have a severe impact on the stop surface, doubling the impact sound, and finally a dent on the edge of the blade that has been involved in the collision, creating an internal stop surface Cause wear and deformation.
Stopper abutment surface that defines the angular range of freedom of mutual rotation between the outer shell-blade assembly and the pinion hub assembly for the purpose of promoting these impact mitigation effects on the critical components of the propeller In addition to using special inserts between the two, the strain is spread to a relatively large number of elastomeric elements by introducing additional elastic elements made of elastomers that bear some of the stress with them, so that these The ability to elastically absorb the impact stress of the elastic shock absorbing element was reduced, and the life of these elastic shock absorbing elements was extended.

According to one known implementation, typical shock absorbers for these types of propellers are generally realized by intentionally configuring the pinion hub in two parts.
A first cylindrical sleeve having a flange is directly fixed to the drive shaft of the propeller, and a plurality of circular recesses are formed on the flange of the cylindrical sleeve so as to be evenly arranged on the circumference of the flange. An elastomeric annular insert is provided inside each circular recess.
The second part of the pinion hub is constituted by a cylindrical sleeve having a terminal flange, which is slid over the cylindrical part of the first sleeve.
The second cylindrical sleeve has conical pinion teeth at one end, and has a plurality of pins arranged uniformly on the circumference of the terminal flange, and the pins extend from the end face of the terminal flange.

To assemble the propeller, the second cylindrical sleeve is slid over the first cylindrical sleeve that is already fixed to the drive shaft, and each elastomer ring provided in each circular recess of the flange of the first cylindrical sleeve. The insert receives in its center hole one of the pins extending from the end flange of the second cylindrical sleeve.
In this way, unforeseen impacts that can occur on the rotating blades of the propeller, as well as impacts between the stop surfaces of the propeller's internal motion mechanism that occur at the start of one-way rotation, can be reduced with the pinion hub assembly. Compression between each pin as well as what happens to the elastic inserts between the metal stop faces of the pitch-determining arc, allowing mutual rotation between the outer shell and the planetary mounted blade assembly It is partially absorbed by the numerous elastomeric annular inserts formed.
In this way, the stress is absorbed by a number of elastomeric elastic inserts and proportionally suppresses the degree of wear and / or degradation of the elastomer's stretch performance.

Of course, the impact-absorbing performance of these elastomeric elastic inserts cannot be eliminated over time, although they can be delayed, so these elements must be replaced periodically, which is usually Performed during the hull maintenance and cleaning process.
If the boat is used for a number of reasons beyond the scheduled maintenance, propellers often make noise before the elastomeric elastic inserts are replaced, as these inserts are extremely degraded. May be activated. This often causes severe deformation of the metal stop surface, which eventually requires expensive repairs and / or replacement of worn parts.
While further extending the life of these elastomeric shock-absorbing elastic inserts, these inserts due to excessive degradation and / or very severe impacts are almost completely destroyed, resulting in functional and functional operation with unbearable noise of the propeller. There is a need or opportunity to prevent significant metal stop surface deformation.
An extremely effective solution has been discovered that can be implemented very easily to meet these needs.

By preventing the situation where the elastic insert fully withstands very large impact stresses when extremely severe impacts occur, the latter life can be extended significantly to double. This is due to the fact that premature degradation of the elastomeric elastic insert and the resulting failure is solely due to an unusual compressive stress, i.e. a very high degree of impact that should normally be relatively rare or rare. Based.
This is because when an extremely severe impact occurs between the metal surfaces, anyway, after the elastomeric shock absorbing elastic insert is elastically deformed to some extent, the deformation of the insert is completely compressed (i.e. It is obtained by introducing a plurality of stop devices that are only partially partial (when the elastic limit is exceeded) but are reached only at such times.
The degree of separate contact of the metal stop device is somewhat arbitrary due to the timing being arbitrary due to the presence of multiple and the elastic action of the multiple elastomer inserts of the metal / metal stop device is not the same Has been determined, which further enhances the overall effectiveness of the novel shock absorber according to the present invention.

Through the bottom of the circular recess housing the respective annular annular inserts of the flanges of the first cylindrical sleeve, which are fixed directly to the drive shaft of the propeller or in any case rotated by the drive shaft, A pin extending from the end face of the end flange of the second circular sleeve, forming a hole coaxial with the axis of the central hole and having a diameter greater than the diameter of the central hole of the elastomeric annular insert and the corresponding engagement pin The shock absorber of the present invention is substantially realized by allowing each pin to extend through a hole formed through the bottom of the respective circular recess of the flange of the first sleeve.
In this way, functionally engages each ring of elastomer, but when the elastomeric annular insert is pressed radially beyond a certain limit, the pin is inserted into the flange of the first tubular sleeve. Contacting the wall of the cylindrical hole intentionally formed through the bottom of the recess containing the object, the remaining impact force (as a result of the impact) is applied to the metal body of the first tubular sleeve.

Of course, the impact of the pin that ultimately acts on the metal wall of the hole formed through the bottom of the respective recess containing the elastomeric annular insert will cause the radial thickness of the elastomeric insert (partially). There is a relatively reduced intensity due to the partial disappearance caused by the compression.
Surprisingly, the ideal thickness of the elastomer ring is about 20 with the final stop at the metal of the flange of the first sleeve of the metal pin of the second sleeve. After pressing from 50% to 50%, in normal use of the propeller, the useful life of the propeller's buffered elastomer ring insert is based on the prior art, and the elastomer insert's full (excess It has been found that it may be more than twice the useful life normally experienced in similar propellers constructed without the introduction of metal / metal stoppers that prevent compression.

Referring to the drawings in which the same parts are denoted by the same reference numerals, FIG. 1 is a simplified example of a pitch adjustable propeller part having a feathering blade embodying the improved shock absorber of the present invention. Partially shown.
A detailed description of all the functional components of this type of propeller is generally well known and goes beyond the purpose of this document solely on the features of the new and improved shock absorber.
However, with reference to FIG. 1, the specific fundamental features of this type of propeller may be briefly reviewed.

The propeller drive shaft 1 rotates a pinion hub 2 which meshes with two or more planetary gears 3 at the base of the handle 4 of each blade 5 held by holes in the outer shell 6 of the propeller.
The outer shell 6 is substantially constituted by joining approximately two or more parts by tangential screws 7 and rotates together with the blade.
The angular range in which the planetary gear 3 of the blade on the pinion hub 2 can move relatively, that is, the freedom in which the blade rotatably held in each hole of the outer shell 6 can be self-oriented under the influence of water resistance From a neutral or central position when the range of degrees, i.e. the boat is sailing (drive shaft 1 idling), the set stop position that determines the constant pitch of the (screw) propeller is the planetary gear of the blade in the embodiment. 3 is set by means of a radial tooth 8 shown as an example, mechanically connected to the drive shaft 1 via an axial extension 9 having a conical pinion end 10 that engages 3. The fan-shaped teeth or radial teeth 8 are formed on the end body 11 thereof, and the teeth 8 which are mechanically connected to the outer shell 6 which is eventually closed by the head 12 of the propeller are inserted into the circular fan section. Cooperates with the stop surface of the recess.

The pinion hub 2 consists of a cylindrical sleeve having two flanges and is shown in more detail in FIGS.
In the embodiment shown, the first cylindrical sleeve 13 is fixed directly to the end of the drive shaft 1 of the propeller, its flange 14 now has seven circular recesses 15, each of which is an elastomeric annular insert 16. Is housed. Although easier to see in the axial projection, the recesses are evenly arranged on the circumference C of the end flange 14 of the first cylindrical sleeve 13.
The second cylindrical sleeve 17 has pinion teeth 2 at one end thereof, and is placed on the cylindrical portion of the first sleeve 13 so as to be able to rotate therearound.
From the end flange 18 of the second sleeve 17, the central hole of the seven inserts 16 of elastomer held in the respective circular recesses 15 of the flange 14 of the first cylindrical sleeve 13 fixed to the drive shaft 1 is penetrated. The seven pins 19 arranged so as to extend are extended.

According to the invention, there is a hole 20 in the bottom of each circular recess 15 which is larger than the diameter of the pin 19 and the diameter of the central hole of the elastomeric annular insert 16. Furthermore, the length of the pin 19 is such that when assembling the parts, the pin is formed with the entire thickness of the annular insert 16 made of elastomer, and the hole 20 formed in the bottom of each circular recess 15 of the flange 14 of the first cylindrical sleeve 13. It extends through.
Details of the structure of the components of the improved shock absorber of the present invention are shown in detail in FIG. 2, a first cylindrical sleeve 13 having a flange and a second cylindrical sleeve 17 having a flange, which constitute the pinion hub 2 of the propeller of FIG. 3 is better understood.

Generally, the diameter of the hole 20 formed through the bottom of the circular recess containing the elastomeric annular insert 16 is several millimeters larger than the pin 19 and the central hole (usually the same) of the elastomeric annular insert 16.
Preferably, the difference between the radial thickness of the bore 20 and the elastomeric annular insert 16 is 20% to 50%, depending on the elastomer characteristics.
More preferably, such a difference corresponds to 20-30% of the radial thickness of the elastomeric ring.

FIG. 1 is a partial cross-sectional view of a pitch-adjustable propeller with a feathering blade provided with an improved shock absorber according to the present invention, and FIGS. 2 and 3, respectively, cooperate with the pinion hub of the propeller. FIG. 3 is a diagram of first and second cylindrical sleeves having a flange to constitute.

Claims (3)

A pitch-adjustable propeller having a feathering blade and a shock absorber, each blade having a planetary gear engaged with a pinion hub (2) rotatable by a drive shaft (1), the pinion hub being a drive shaft The first flanged cylindrical sleeve (13) fixed to (1) and the cylindrical part of the first flanged cylindrical sleeve (13) are slid and covered, and the second flanged cylindrical sleeve (17) ends with the pinion. The first flanged cylindrical sleeve (13) is arranged evenly around the circumference and has a plurality of circular recesses (15) each containing an elastomeric elastic elastic insert (16) (14). And the second flanged cylindrical sleeve (17) has an end flange (18) having a plurality of pins (19) arranged evenly around the circumference, each pin being a respective elastomer. A pitch-adjustable propeller having a dampening device that engages the annular elastic insert (16) of the mer, wherein the elastomeric annular elastic insert (16) in the flange (14) of the cylindrical sleeve (13) with the first flange The engagement pin (19) of the elastomeric annular elastic insert (16) is coaxial with the axis of the central hole of the elastomeric annular elastic insert (16). A central hole to be engaged and a hole (20) having a diameter larger than the diameter of the corresponding engaging pin (19) are provided, said pins being each of the flange (14) of said cylindrical sleeve (13) with said first flange. A pitch-adjustable propeller having a shock absorber, characterized in that it extends through the hole (20) in the bottom of the circular recess (15) of the. The difference between the radius of the hole (20) passing through the bottom of each circular recess (15) and the radial thickness of the elastomeric annular elastic insert (16) is expressed in percent as the elastomeric annular elastic insert (16). A pitch adjustable propeller with a shock absorber according to claim 1 which is between 20% and 50% of the thickness. The pitch adjustable propeller with shock absorber according to claim 2, wherein the difference is between 20% and 30% of the thickness.

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